// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This file is an internal atomic implementation, use base/atomicops.h instead.

#ifndef BASE_ATOMICOPS_INTERNALS_MAC_H_
#define BASE_ATOMICOPS_INTERNALS_MAC_H_

#include <libkern/OSAtomic.h>

namespace base {
namespace subtle {

    inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
        Atomic32 old_value,
        Atomic32 new_value)
    {
        Atomic32 prev_value;
        do {
            if (OSAtomicCompareAndSwap32(old_value, new_value,
                    const_cast<Atomic32*>(ptr))) {
                return old_value;
            }
            prev_value = *ptr;
        } while (prev_value == old_value);
        return prev_value;
    }

    inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr,
        Atomic32 new_value)
    {
        Atomic32 old_value;
        do {
            old_value = *ptr;
        } while (!OSAtomicCompareAndSwap32(old_value, new_value,
            const_cast<Atomic32*>(ptr)));
        return old_value;
    }

    inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
        Atomic32 increment)
    {
        return OSAtomicAdd32(increment, const_cast<Atomic32*>(ptr));
    }

    inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
        Atomic32 increment)
    {
        return OSAtomicAdd32Barrier(increment, const_cast<Atomic32*>(ptr));
    }

    inline void MemoryBarrier()
    {
        OSMemoryBarrier();
    }

    inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
        Atomic32 old_value,
        Atomic32 new_value)
    {
        Atomic32 prev_value;
        do {
            if (OSAtomicCompareAndSwap32Barrier(old_value, new_value,
                    const_cast<Atomic32*>(ptr))) {
                return old_value;
            }
            prev_value = *ptr;
        } while (prev_value == old_value);
        return prev_value;
    }

    inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
        Atomic32 old_value,
        Atomic32 new_value)
    {
        return Acquire_CompareAndSwap(ptr, old_value, new_value);
    }

    inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value)
    {
        *ptr = value;
    }

    inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value)
    {
        *ptr = value;
        MemoryBarrier();
    }

    inline void Release_Store(volatile Atomic32* ptr, Atomic32 value)
    {
        MemoryBarrier();
        *ptr = value;
    }

    inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr)
    {
        return *ptr;
    }

    inline Atomic32 Acquire_Load(volatile const Atomic32* ptr)
    {
        Atomic32 value = *ptr;
        MemoryBarrier();
        return value;
    }

    inline Atomic32 Release_Load(volatile const Atomic32* ptr)
    {
        MemoryBarrier();
        return *ptr;
    }

#ifdef __LP64__

    // 64-bit implementation on 64-bit platform

    inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
        Atomic64 old_value,
        Atomic64 new_value)
    {
        Atomic64 prev_value;
        do {
            if (OSAtomicCompareAndSwap64(old_value, new_value,
                    reinterpret_cast<volatile int64_t*>(ptr))) {
                return old_value;
            }
            prev_value = *ptr;
        } while (prev_value == old_value);
        return prev_value;
    }

    inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr,
        Atomic64 new_value)
    {
        Atomic64 old_value;
        do {
            old_value = *ptr;
        } while (!OSAtomicCompareAndSwap64(old_value, new_value,
            reinterpret_cast<volatile int64_t*>(ptr)));
        return old_value;
    }

    inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr,
        Atomic64 increment)
    {
        return OSAtomicAdd64(increment, reinterpret_cast<volatile int64_t*>(ptr));
    }

    inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr,
        Atomic64 increment)
    {
        return OSAtomicAdd64Barrier(increment,
            reinterpret_cast<volatile int64_t*>(ptr));
    }

    inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr,
        Atomic64 old_value,
        Atomic64 new_value)
    {
        Atomic64 prev_value;
        do {
            if (OSAtomicCompareAndSwap64Barrier(
                    old_value, new_value, reinterpret_cast<volatile int64_t*>(ptr))) {
                return old_value;
            }
            prev_value = *ptr;
        } while (prev_value == old_value);
        return prev_value;
    }

    inline Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr,
        Atomic64 old_value,
        Atomic64 new_value)
    {
        // The lib kern interface does not distinguish between
        // Acquire and Release memory barriers; they are equivalent.
        return Acquire_CompareAndSwap(ptr, old_value, new_value);
    }

    inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value)
    {
        *ptr = value;
    }

    inline void Acquire_Store(volatile Atomic64* ptr, Atomic64 value)
    {
        *ptr = value;
        MemoryBarrier();
    }

    inline void Release_Store(volatile Atomic64* ptr, Atomic64 value)
    {
        MemoryBarrier();
        *ptr = value;
    }

    inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr)
    {
        return *ptr;
    }

    inline Atomic64 Acquire_Load(volatile const Atomic64* ptr)
    {
        Atomic64 value = *ptr;
        MemoryBarrier();
        return value;
    }

    inline Atomic64 Release_Load(volatile const Atomic64* ptr)
    {
        MemoryBarrier();
        return *ptr;
    }

#endif // defined(__LP64__)

} // namespace subtle
} // namespace base

#endif // BASE_ATOMICOPS_INTERNALS_MAC_H_
